1. Field of the Invention
Earlier Logue patents refer to the related devices as xe2x80x9cpolar coordinates sensorxe2x80x9d i.e. a hemispherical rotating field generator.
This invention employs a toroidal wound pot-core half generating a rotating magnetic field fringing through the excitation turns.
2. Related Art
Tesla U.S. Pat. No. 382,280 disclosed a ring built up of insulated annular iron plates and wound with poly-phase distributions forming an early rotating field stator for generator/motor use. Field utility was limited to the winding window of the toroidal stator. In the cited Logue patent applications the rotating hemispherical flux fringing from the plane of this toroidal stator (pot-core half) was utilized for inducing eddy currents in conducting workpieces e.g. aircraft splice joints. The driving flux is directly coupled from the toroidal plane to the workpiece through the poly-phase excitation turns.
The polar coordinates signal disclosed in the ascending Logue patents is actually formed by successive revolutions of the hemispherical driving field acceleration; the axis of which is displaced by an asymmetry (flaw) in the eddy current reflection. This is a rotary type of parametric pumping. Acceleration of the driving field revolutions is explained and illustrated in Logue U.S. Pat. No. 5,909,118 (obviously frequency modulation).
A primary object of the invention is a tighter focusing of the probe pattern fringing from the toroidal driving plane. Tightly fitting a copper toroid concentrically around a pot-core half eliminates the flux spilling gap resulting from a previous method of winding the excitation distributions around the pot-core first (Logue U.S. Pat. No. 6,265,871). An all encompassing toroidal excitation winding method is show in FIG. 1, in which the poly-phase distributions thread through the toroidal window, encircling the pick-up coil, driving toroid and the mentioned thick copper toroid (a Lenz lens). A second object of the invention is an arrangement of concentric pot-core halves on increasing radii for generating at least two radii of concentric eddy current hemispheres in a conducting workpiece, the pick-up coil of each pot-core generating a flaw signal in response to a flux asymmetry. This increasing driving sensing radii equals differing depths of eddy current excitation reflection. As taught in Logue U.S. Pat. No. 6,265,871 individuality of predetermined angular velocities is provided between concentric toroidal cores (radii isolation of excitation current phase/amplitude is obviously possible). A further object of the disclosure is an excitation method similar to well known television picture tube electron beam/s deflection by a predetermined current modulation of the toroidal yoke windings (toroidal probe) i.e the x-y excitation axes of a resultant vectorial fringing magnetic field. In the light of television, radar and Logue U.S. Pat. Nos. 6,265,871 6,229,305 6,271,664 6,271,664 the underling principles of this method are understood.
The preferred pick-up assembly to date is a pot-core half with a pick-up coil having many turns of small guage magnet wire e.g. 42 ga., wound around the central pole (184, FIG. 1) filling the annular coil space 179. For more complete annular space filling of the pick-up core, flat small guage magnet wire may be spool-less wound, using H. P. Reid Co (trademark). adhesive pre-coated voice-coil wire. Alternately multiple parallel smaller gauge magnet wires e.g. 46 gauge, may be used.
This high-density method of pick-up coil winding accentuates the z-axis permeability modulation of the pot-core half, increasing ramping signal build-up re: Logue U.S. Pat. No. 5,909,118 (see Oscillatory Signal Build-up above). As taught in Logue application Ser. No. 09/467,599 a polar coordinates sensor may be reduced to a ferrite pot-core half (integral x-y-z axes of permeability) having a pick-up coil of many turns wound around the central pole 284 (FIG. 1), combined with a rotating driving field generated by sine-cosine currents flowing in sine-cosine excitation windings wound through mounting hole 193 (now winding hole 193) in FIG. 1. The pot-core half must be segment-less (no lead slots)